A rotor is a rotating component of a rotating machine and facilitates the conversion of torque generated by a motor of a turbomachine into useful work. The rotor comprises an axial shaft and different components mounted on the axial shaft. The axial shaft transmits the torque generated by a motor of the turbomachine. The rotor utilizes the torque in order to perform a wide range of desired applications. For example, a rotor for a compressor comprises one or more impellers mounted on the axial shaft for compressing a working fluid in order to increase the pressure and flow rate of the working fluid. Furthermore, the rotor can comprise multiple stages, for example, a rotor for a three stage compressor comprises three impellers arranged in succession, wherein each of the impellers is circumferentially disposed on the axial shaft. Such a multi stage rotor in a compressor is advantageous as the amount of work performed is enhanced manifold times, resulting in a higher compression ratio compared to a single stage compressor.
Traditionally, a rotor comprising multiple stages is constructed by assembling the aforementioned individual stages at designated locations on the axial shaft. The axial shaft is hereof a monolithic unit. The individual stages are then shrink fitted at the designated locations on the axial shaft. During this process of construction, either a casing of the rotor is kept open in order to obtain a clear view of the axial shaft or the casing of the rotor is to be provided with margin space to facilitate the assembly of the different stages on the axial shaft, and as well as for the free movement of equipments that are utilized for assembling the rotor. The margin space is then covered appropriately so that the flow profile inside the compressor remains unaffected.
The aforementioned rotor assembly is disadvantageous. In case of enormous rotors, for example a ten stage compressor, the length and weight of the axial shaft increase tremendously. This overburdens the transportation of the individual components of the motor, and also mandates more space for assembling the individual components in order to construct the rotor. Furthermore, the equipments used for facilitating the assembly require more space for its movement.
Additionally, if the axial shaft suffers an irreparable damage or a crack, the entire rotor has to be dismantled and the entire axial shaft has to be replaced for repairing the damaged axial shaft, which is a cumbersome task.
Therefore, the design and construction of the rotors of the aforementioned type is a challenging task.